dynamic modeling of a strip valve

[jayidian]

that's look good! i'll try to open that one..

[WebPilot]

Additional material on 'equivalent stiffness' forthcoming.

Please be patient, 'cause it's summer here; time for bikes, working on bikes and cars, chasing slow women, concerts and everything else that is fun under the sun.

[tritile]

oh, man!

we lost all the pictures of this topic =/

[WebPilot]

☢ links verified

[tritile]

Does anyone have webpilot's e-mail address? I'd like to ask him if he still has the pictures of this topic. Links are no longer working, and I believe they are pretty important. This topic is one of the most significant in the whole forum.

[Mike Everman]

Right click the mail icon below Webpilot's name on one of his posts, and email him to that address. It's the only address I have. I had hoped that Forrest would put his diagrams directly on this thread so they would be available forever, and made him a moderator so he could upgrade and edit as he saw fit, but unfortunately all of his beautiful diagrams were hosted on a free site. They have disappeared twice or so, which is unfortunate. It's a lot of work for him to re-host and re-link them all, so I'm hoping next time that he will just put it all here instead of links.
Mike

[tritile]

I'm ready to help somehow if he ever need. Unfortunately I believe that only he can edit the old posts and add the pictures. I'll send him an e-mail.

[tritile]

Mike, I can't see the e-mail icon you say. I don't know if it is something in my browser or what. Could you send me his address by private message?

[ZSartell]

I would really like to read through this thread in its entirety, but without the pictures and diagrams I am lost. Does anyone have these to share?

[Mike Everman]

You and me both. It was a fine piece of work. I made him a moderator so he could edit this thread to his heart’s content, hoping he’d embed his figures, but he hosted them all on free picture services that went away.
Tragic.

[Alex Eng]

Well, since this topic is on the top, and if someone is still interested in dynamic modeling of a reed valve petal of a valved pulsejet - our program uses 2 models: quasi-static and dynamic. You can select a model in the program menu, and it's very simple. You can even compare the modeling results with both models .

It is fundamentally important that it is 100500% impossible to apply even the most complex and most accurate model of 1 engine element in practice without the engine itself. Moreover, there will be no useful results for practice if the reed valve model works on its own without the engine model - these will be just pretty pictures, absolutely useless for anything .

Unfortunately, these pictures are now impossible to view, the user Webpilot deleted them. But the main rule always works - any pulsejet element can be modeled only in one case: if the element model works together with the full engine model. Because only in this case you can find the effect of a pretty picture on the working process and engine parameters. Otherwise, there is no point in wasting time on pretty pictures .

If I explain it briefly, the reason is simple - it is the delay and rebound of the petal from the grid and from its limiter. All this reduces the air flow during the vacuum in the combustion chamber and reduces the pressure in the chamber due the backflow when the delay in closing. As a result, the movement of the petal depends not only on the design, but also on the nature of the pressure change in the chamber, and the nature of the pressure change there depends on the movement of the petal. Then it turns out that the criterion for the petal's operation is not beautiful pictures of its bending in time, but the air consumption, fuel consumption and engine thrust. Therefore, without entire engine model, it is impossible to find out which petal is good, and which is bad in principle and by definition. And I really hope that the Webpilot user modeled the petal as part of his engine model and identified the effect of the petal parameters on thrust and specific fuel consumption .

In our program, the dynamic model of petal movement is simple, but it gives everything we want from it. You can even enter different petal thicknesses and see what happens. Interestingly, there is some optimal petal thickness - different engines work differently with different petal thicknesses but work worse with very thin and very thick petals .

Soon we will make it possible very easily to parametrically study any engine with any petal automatically. But for now, you can already do it step by step, manually repeating the simulation with different petal sizes. Even on your own telephone!

And it can be very interesting picture too...

[Mike Everman]

Interesting, Alex, Thanks. some of us will definitely check this out!